Astronomy: July Skies

The Moon begins this month one day from new phase, which also happens to be the only total solar eclipse of 2019, beginning in the western South Pacific, cutting across Chile, and ending at Buenos Aires. Two days later, July 4, sees three thin, waxing crescent lunar events: an occultation of Mars (for us, a close approach); another close approach of Mercury; and the Moon glides through the star field of the Beehive Cluster – these are listed as separate events, but all three occur together. On the 13th, Jupiter is a scant 2 degrees south of our satellite. The 16th has another grouping of events: Saturn is occulted for Southern Hemisphere viewers, a very close conjunction for us in the north; Pluto is also occulted, again in the south; and, following 2 weeks after a solar eclipse, of course, a partial lunar eclipse occurs, but this one will only be visible in the Southern Hemisphere. On the 25th, Uranus meets up with the Moon, 5 degrees north.

Mercury is seen only with difficulty low in the western horizon early in the month; gradually disappearing as it crosses in front of the Sun.

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Venus is disappearing into the morning eastern sky, as it rounds in its orbit behind the Sun. It won’t be visible again until September, in the western evening sky.

Mars is nearing superior conjunction, when it passes behind the Sun in early September. Catch a fleeting glimpse of it now while you can, like on the 4th, mentioned above.

Jupiter dominates the southern sky all through the summer. It’s high in the sky as twilight darkens into night, almost straight south at midnight, among the stars of western Sagittarius. This is a good time to use binoculars or a telescope to see the Galilean moons, which move rapidly, changing position each evening. These objects, all but one larger than our Moon, were first seen by Galileo in 1610, thus bearing his name. The two inner moons orbit very quickly, with periods of 1.7 and 3.5 days, respectively. Compare those orbital times with our Moon that takes 27.3 days to get around the Earth once. Watch for the nearby Moon in the 13th.

Saturn rises in the east in eastern Sagittarius, crossing the sky all night and bracketing The Archer with its partner gas-giant planet, Jupiter. The Moon is nearby on July 16. Saturn will be positioned well throughout the month and the rest of the summer.

Uranus is fleetingly visible in the morning sky, just before sunup.

Neptune rises after midnight, disappearing in the daytime at sunrise.

The south delta Aquariid meteor shower peaks on July 28.

James Edgar has had an interest in the night sky all his life. He joined The Royal Astronomical Society of Canada in 2000, was National President for two terms, is now the Editor of the renowned Observer’s Handbook, and Production Manager of the bi-monthly RASC Journal. The IAU named asteroid 1995 XC5 “(22421) Jamesedgar” in his honour.
 

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